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run code in 300+ PHP versions simultaneously
<?php $str = "racecar"; $pal = ""; for($a=0; $a<strlen($str); $a++) { for($z=0; $z<strlen($str); $z++) $subs = substr($str, $a, $z); if( $subs == strrev($subs) and strlen($subs) > strlen($pal) ) { echo $a; $pal = $subs; } } echo $pal;

preferences:
33.61 ms | 402 KiB | 5 Q